Experimental app list: Added a current page indicator to the launcher.

ui/app_list/views/contents_switcher_view.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/app_list/views/contents_switcher_view.h"
 
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/views/contents_view.h"
+#include "ui/views/background.h"
 #include "ui/views/controls/button/custom_button.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/layout/box_layout.h"
+#include "ui/views/layout/fill_layout.h"
 
 namespace app_list {
 
 namespace {
 
-const int kPreferredHeight = 32;
+const int kPageIndicatorHeight = 1;
+const int kButtonImageSize = 32;
+const int kPreferredHeight = kButtonImageSize + kPageIndicatorHeight;
 const int kButtonSpacing = 4;
 
+class ContentsPageIndicatorView : public views::View {
+ public:
+  ContentsPageIndicatorView() {};
+  virtual ~ContentsPageIndicatorView() {};
+
+  // Overridden from views::View:
+  virtual gfx::Size GetPreferredSize() const OVERRIDE {
+    return gfx::Size(0, kPageIndicatorHeight);
+  };
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ContentsPageIndicatorView);
+};
+
 }  // namespace
 
 ContentsSwitcherView::ContentsSwitcherView(ContentsView* contents_view)
     : contents_view_(contents_view), buttons_(new views::View) {
   AddChildView(buttons_);
 
   buttons_->SetLayoutManager(new views::BoxLayout(
       views::BoxLayout::kHorizontal, 0, 0, kButtonSpacing));
 }
 
 ContentsSwitcherView::~ContentsSwitcherView() {}
 
 void ContentsSwitcherView::AddSwitcherButton(int resource_id, int page_index) {
   views::ImageButton* button = new views::ImageButton(this);
+  button->SetPreferredSize(gfx::Size(kButtonImageSize, kButtonImageSize));

[Matt Giuca, 2014/07/09 07:01:20]

What does setting this do? (Why is it needed now and not before?)

[calamity, 2014/07/09 08:02:54]

It should have been there before. It has no effect on the current app list. It's
for semantic layout correctness. It tells the ImageButton what size to be when
it has no image set. We can remove this if you really want.

   if (resource_id) {
     button->SetImage(
         views::CustomButton::STATE_NORMAL,
         ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(resource_id));
   }
   button->set_tag(page_index);
-  buttons_->AddChildView(button);
+
+  // Add an indicator for the current launcher page.
+  app_list::ContentsPageIndicatorView* indicator =
+      new app_list::ContentsPageIndicatorView();
+  indicator->set_background(
+      views::Background::CreateSolidBackground(app_list::kPagerSelectedColor));
+  indicator->SetVisible(false);
+  page_active_indicators_.push_back(indicator);
+
+  // A container view that will consume space when its child is not visible.
+  // TODO(calamity): Remove this once BoxLayout supports space-consuming
+  // invisible views.
+  views::View* indicator_container = new views::View();
+  indicator_container->SetLayoutManager(new views::FillLayout());
+  indicator_container->AddChildView(indicator);
+
+  // View containing the indicator view and image button.
+  views::View* button_container = new views::View();
+  views::BoxLayout* layout_manager =
+      new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 0);
+  layout_manager->set_main_axis_alignment(
+      views::BoxLayout::MAIN_AXIS_ALIGNMENT_CENTER);
+  button_container->SetLayoutManager(layout_manager);
+  button_container->AddChildView(indicator_container);
+  button_container->AddChildView(button);
+
+  buttons_->AddChildView(button_container);
 }
 
 gfx::Size ContentsSwitcherView::GetPreferredSize() const {
   return gfx::Size(buttons_->GetPreferredSize().width(), kPreferredHeight);
 }
 
 void ContentsSwitcherView::Layout() {
   gfx::Rect rect(GetContentsBounds());
 
   // Makes |buttons_| horizontally center and vertically fill.
   gfx::Size buttons_size(buttons_->GetPreferredSize());
   gfx::Rect buttons_bounds(rect.CenterPoint().x() - buttons_size.width() / 2,
                            rect.y(),
                            buttons_size.width(),
                            rect.height());
   buttons_->SetBoundsRect(gfx::IntersectRects(rect, buttons_bounds));
 }
 
 void ContentsSwitcherView::ButtonPressed(views::Button* sender,
                                          const ui::Event& event) {
   contents_view_->SetActivePage(sender->tag());
 }
 
+void ContentsSwitcherView::SelectedPageChanged(int old_selected,
+                                               int new_selected) {
+  int num_indicators = static_cast<int>(page_active_indicators_.size());
+  if (old_selected >= 0 && old_selected < num_indicators)
+    page_active_indicators_[old_selected]->SetVisible(false);
+
+  if (new_selected >= 0 && new_selected < num_indicators)
+    page_active_indicators_[new_selected]->SetVisible(true);
+}
+
 }  // namespace app_list